1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images before sunset (above) and Infrared images after sunset (below) revealed Above-Anvil Cirrus Plume (AACP) features associated with severe thunderstorms that were producing large hail (SPC storm reports) over the Texas Panhandle on 22 March 2019.

A plot of 00 UTC rawinsonde data from Amarillo, Texas (below) showed that the Equilibrium Level (EL) and the tropopause was around 11 km — where the air temperature was near -60ºC, which is highlighted by a red enhancement on the Infrared imagery.  The calculated Maximum Parcel Level was around 13 km — where the air temperature was near -50ºC, which is highlighted by a yellow enhancement on the Infrared imagery; the MPL was the likely altitude of the AACP. Note on the 0245 UTC and 0258 UTC images that two of the hail reports were located near the colder (darker red to black) pixels of overshooting tops, which were close to the southern end of the warmer (brighter yellow) pixels of the AACP.

As pointed out on the Satellite Liaison Blog, some of the accumulating hail remained on the ground during the overnight hours — and the next morning, a hail swath signature was evident on GOES-16 Visible and Near-Infrared “Snow/Ice” (1.61 µm) imagery (below); the longest swath stretched for a distance of about 40 miles. The hail appeared as shades of white in the Visible imagery, and as darker shades of black in the Snow/Ice imagery (since ice is a strong absorber of radiation at the 1.61 µm wavelength). Note how the darker signature of wet soil (water is also a strong absorber at 1.61 µm) persisted on Near-Infrared  imagery even after the brighter signature of the melting hail swath disappeared on Visible imagery. Accumulating hail occurred over portions of Interstate 27 between Amarillo and Canyon, and Interstate 40 between Wildorado and Bushland; one trained storm spotter reported that the hail was several inches deep just northwest of Amarillo (Local Storm Reports).

As the morning sun was beginning to warm the soil, GOES-16 Land Surface Temperature images at 1402 and 1502 UTC or 9:02 and 10:02 AM local time (below) depicted temperatures up to 10ºF cooler within the hail swath compared to adjacent bare ground.

With ample illumination from the Moon (in the Waning Gibbous phase, at 92% of Full) a “visible image at night” was provided by the Suomi NPP VIIRS Day/Night Band (0.7 µm), which showed the hall swath at 0748 UTC or 2:48 AM local time — a toggle between that Day/Night Band image and an early morning GOES-16 Visible image is shown bellow.

View only this post Read Less

A toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) images (above) showed Category 4 Cyclone Veronica off the northern coast of Western Australia at 1716 UTC on 21 March 2019. Ample illumination from a Full Moon maximized the “visible image at night” capability of the Day/Night Band.

In a comparison of Microwave images from Suomi NPP ATMS at 1716 UTC and from GCOM-W1 AMSR2 at 1732 UTC (below), an eyewall that was nearly completely closed was apparent. Suomi NPP and GCOM-W1 images courtesy of William Straka, CIMSS.

A DMSP-17 SSMIS Microwave (85 GHz) image at 2246 UTC from the CIMSS Tropical Cyclones site is shown below. The deep-layer Wind Shear at 21 UTC was low (green contours), and Sea Surface Temperature values were quite high — both factors favorable for continued intensification as Veronica moved slowly toward the coast.

2.5-minute interval rapid scan Himawari-8 Infrared Window (10.4 µm) images (below) showed increasing organization to the eyewall structure. At times the cloud-top infrared brightness temperatures were -90ºC and colder (yellow pixels embedded within darker purple). Note: the rapid scan sector was re-poositioned eastward at 0100 UTC (to monitor Cyclone Trevor), so 10-minute imaging resumed after that time.

After sunrise, rapid scan Himawari-8 “Red” Visible (0.64 µm) images (below) revealed that the large eye was completely cloud-filled.

View only this post Read Less

GOES-17 (GOES-West) “Red” Visible (0.64 µm) images (above) showed that it was generally cloud-free across much of eastern Alaska and northwestern Canada on 19 March 2019 — the abundant solar insolation help to warm surface temperatures to record levels for the month of March at locations such as Sitka (high=67ºF) and Yakutat (high=60ºF) along the Alaska Panhandle, and at Yohin Lake (high=71ºF) in the Canadian Northwest Territories. The 70ºF at Klawock was the earliest occurrence of 70ºF on record for the state of Alaska, and the 71ºF at Yohin Lake was the earliest 70ºF on record for the Northwest Territores. In the eastern Interior of Alaska, daily temperature records for 19 March were set at Eagle (high=55ºF) and Northway (high=50ºF).

GOES-17 Air Mass RGB images from the AOS site (below) helped to highlight the anomalous mid-tropospheric ridge and warm lower-tropospheric temperatures over western North America — note the northwestward surge of green hues that are more characteristic of warm subtropical air masses south of the polar jet stream over the central Pacific Ocean. Note that GOES-17 was conducting a test of the Mode 6 scan schedule, so Full Disk images were available every 10 minutes.

Unreasonably hot: Here's a sampling (not complete) of March and seasonal all-time record high temps that have been set in the past few days in Alaska and northwest Canada. H/T @Pat_wx for great tweets on the Canadian records. #Arctic #akwx #ntwx #ykwx @Climatologist49 @DaveSnider pic.twitter.com/g1uFLVAzPb

— Rick Thoman (@AlaskaWx) March 20, 2019

Third day of record-smashing heat in the northwest yesterday. Up to 21.8°C in Yohin Lake, and several more March records were set or improved from previous days. Cooling down a bit today, but remaining much above normals all week. #Arctic #Yukon #NWT pic.twitter.com/vLH6luYrkW

— Patrick Duplessis (@Pat_wx) March 20, 2019

View only this post Read Less

GOES-16 (GOES-East) Shortwave Infrared (3.9 µm) images (above) revealed the thermal anomaly or “hot spot” of a fire burning at the Intercontinental Terminals Company petrochemical plant in Deer Park, Texas on 18 March 2019. Although the thermal signature was often partially masked by the passage of high clouds overhead, it was still evident for much of the time period (0202-1457 UTC, or 9:02pm-9:57am CDT). The fire started around 1530 UTC (10:30am CDT) on 17 March.

Comparisons of 2-km resolution (at satellite subpoint) GOES-16 Shortwave Infrared and 375-meter resolution VIIRS Shortwave Infrared (3.74 µm) imagery from Suomi NPP (at 0741 UTC) and NOAA-20 (at 0835 UTC) are shown below. The thermal signature is better defined and more accurately located using the higher-resolution VIIRS imagery.

A comparison of 1-km resolution NOAA-19 AVHRR and 2-km resolution GOES-16 Shortwave Infrared images at 1132 UTC is shown below. This happened to be at a time when the GOES-16 thermal signature was being masked by high clouds overhead. The fire was located northeast of the Houston Hobby (station identifier KHOU) and Ellington (station identifier KEFD) airports.

In a sequence of GOES-16 “Red” Visible (0.64 µm), Near-Infrared “Vegetation” (0.86 µm) and Near-Infrared “Snow/Ice” (1.61 µm) images (below), the dark-colored smoke plume was most obvious in the Near-Infrared imagery — this is due to the fact that vegetation is more reflective at those wavelengths, helping to enhance the smoke/surface contrast. The smoke had drifted as far westward as Austin and Kerrville, a distance of over 100 miles.

===== 19 March Update =====

The Deer Park Fire continued to burn uncontrolled on 19 March — 1-minute Mesoscale Domain Sector GOES-16 Visible, Near-Infrared and Shortwave Infrared images (above) showed that while the passage of mid/upper-level clouds often obscured the dark-colored smoke plume, a signature of the hot thermal anomaly was seen almost continuously. Note that the color enhancement applied to the Shortwave Infrared imagery is different from the one used in the 18 March examples.

===== 22 March Update =====

There was a brief re-ignition of the fire that began at 2035 UTC on 22 March, as shown by 1-minute GOES-16 Visible, Near-Infrared and Shortwave Infrared images (above). The thermal anomaly of the fire was only apparent for about 50 minutes — reaching a peak infrared brightness temperature of 48.4ºC at 2044 UTC — while the dark smoke continued to spread to cover a north-south distance of over 10 miles in 90 minutes, moving over Interstate 10 and the cities of Channelview and Highlands.

View only this post Read Less